diff --git a/Lib/test/test_colorsys.py b/Lib/test/test_colorsys.py
new file mode 100644
index 0000000..1ef7b0c
--- /dev/null
+++ b/Lib/test/test_colorsys.py
@@ -0,0 +1,76 @@
+import unittest, test.test_support
+import colorsys
+
+def frange(start, stop, step):
+    while start <= stop:
+        yield start
+        start += stop
+
+class ColorsysTest(unittest.TestCase):
+
+    def assertTripleEqual(self, tr1, tr2):
+        self.assertEqual(len(tr1), 3)
+        self.assertEqual(len(tr2), 3)
+        self.assertAlmostEqual(tr1[0], tr2[0])
+        self.assertAlmostEqual(tr1[1], tr2[1])
+        self.assertAlmostEqual(tr1[2], tr2[2])
+
+    def test_hsv_roundtrip(self):
+        for r in frange(0.0, 1.0, 0.2):
+            for g in frange(0.0, 1.0, 0.2):
+                for b in frange(0.0, 1.0, 0.2):
+                    rgb = (r, g, b)
+                    self.assertTripleEqual(
+                        rgb,
+                        colorsys.hsv_to_rgb(*colorsys.rgb_to_hsv(*rgb))
+                    )
+
+    def test_hsv_values(self):
+        values = [
+            # rgb, hsv
+            ((0.0, 0.0, 0.0), (  0  , 0.0, 0.0)), # black
+            ((0.0, 0.0, 1.0), (4./6., 1.0, 1.0)), # blue
+            ((0.0, 1.0, 0.0), (2./6., 1.0, 1.0)), # green
+            ((0.0, 1.0, 1.0), (3./6., 1.0, 1.0)), # cyan
+            ((1.0, 0.0, 0.0), (  0  , 1.0, 1.0)), # red
+            ((1.0, 0.0, 1.0), (5./6., 1.0, 1.0)), # purple
+            ((1.0, 1.0, 0.0), (1./6., 1.0, 1.0)), # yellow
+            ((1.0, 1.0, 1.0), (  0  , 0.0, 1.0)), # white
+            ((0.5, 0.5, 0.5), (  0  , 0.0, 0.5)), # grey
+        ]
+        for (rgb, hsv) in values:
+            self.assertTripleEqual(hsv, colorsys.rgb_to_hsv(*rgb))
+            self.assertTripleEqual(rgb, colorsys.hsv_to_rgb(*hsv))
+
+    def test_hls_roundtrip(self):
+        for r in frange(0.0, 1.0, 0.2):
+            for g in frange(0.0, 1.0, 0.2):
+                for b in frange(0.0, 1.0, 0.2):
+                    rgb = (r, g, b)
+                    self.assertTripleEqual(
+                        rgb,
+                        colorsys.hls_to_rgb(*colorsys.rgb_to_hls(*rgb))
+                    )
+
+    def test_hls_values(self):
+        values = [
+            # rgb, hls
+            ((0.0, 0.0, 0.0), (  0  , 0.0, 0.0)), # black
+            ((0.0, 0.0, 1.0), (4./6., 0.5, 1.0)), # blue
+            ((0.0, 1.0, 0.0), (2./6., 0.5, 1.0)), # green
+            ((0.0, 1.0, 1.0), (3./6., 0.5, 1.0)), # cyan
+            ((1.0, 0.0, 0.0), (  0  , 0.5, 1.0)), # red
+            ((1.0, 0.0, 1.0), (5./6., 0.5, 1.0)), # purple
+            ((1.0, 1.0, 0.0), (1./6., 0.5, 1.0)), # yellow
+            ((1.0, 1.0, 1.0), (  0  , 1.0, 0.0)), # white
+            ((0.5, 0.5, 0.5), (  0  , 0.5, 0.0)), # grey
+        ]
+        for (rgb, hls) in values:
+            self.assertTripleEqual(hls, colorsys.rgb_to_hls(*rgb))
+            self.assertTripleEqual(rgb, colorsys.hls_to_rgb(*hls))
+
+def test_main():
+    test.test_support.run_unittest(ColorsysTest)
+
+if __name__ == "__main__":
+    test_main()